Synthetic fibers such as for example polyesters fibers, polyamide fibers, etc., because of their low electric conductivity, are easy to generate static electricity by friction. Consequently, in using fabrics comprising such synthetic fibers, various obstacles accompanying attachment of dusts, electric discharge, etc. are generated. In order to solve these problems, incorporating electrically conductive fibers in textile goods is known. For example, metal fibers, metallized fibers, fibers mixed with carbon black and/or an electrically conductive substance, etc. have been proposed as the electrically conductive fibers [Japanese Patent Publication Nos. 44,579/1978 and 37,322/1981, Japanese Patent Kokai (Laid-open) No. 193,520/1982].
These electrically conductive fibers, however, have not been satisfactory because they have various problems in one or more yarn properties, production of mixed knitted goods and mixed woven goods with other fibers, and the hue and dyeability of these goods.
Further, conjugate fibers comprising an alloy as the core and a thermoplastic polymer as the sheath are known as fiber, having excellent electric conductivity and dyeability [Japanese Patent Kokai (Laid-open) No. 11,909/1976]. However, for reasons that the alloy, a core, has a low viscosity and a high surface tension, and besides that such an apparatus as shown in FIG. 5 is used to produce the conjugate fibers, it is very difficult to supply the fused alloy at a constant rate. It is therefore difficult to make the diameter of the core definite, and thin portions and thick portions appear irregularly. As a result, the fused alloy is broken, in many cases, at the thin portions at the time of drawing, which makes not only the diameter of the core alloy variable, but also the length of the core alloy and the hollow nonuniform. Because of this, not only the appearance is much damaged, but also satisfactory electric conductivity and yarn properties are difficult to obtain, and so such conjugate fibers have not been goods which can be placed on the market.
Particularly, when thin conjugate fibers (diameter, generally 50 .mu.m or less) used in clothing, etc. are produced, it is very difficult to supply a fused metal continuously and in a definite amount. For all the devices, conjugate fibers having satisfactory qualities as well as an apparatus and a method for producing them are not yet developed.